Curry suffered a foot injury in the Warriors' 116-100 defeat in Game 3 at TD Garden on Wednesday.
The two-time MVP had insisted he would not miss Game 4 and head coach Steve Kerr confirmed Curry will be available for the entirety of Friday's critical clash.
"He's feeling well, just went through shootaround. He said he's ready to go," Kerr told reporters.
The Warriors trail the series 2-1 and will have history against them if the Celtics claim a third win in four.
Only one team in NBA Finals history has come back from a 3-1 deficit to prevail, the Cleveland Cavaliers famously doing so against the Warriors in 2016.
Curry has scored 26.8 points per game so far in the postseason. He has averaged 31.3 across the first three games of the Finals.